"Good" Fat Protein May Protect Blood Vessels

While there is much we do not know, medical science has greatly advanced in recent years in its understanding of cardiovascular disease.

We have learned, for example, that there is a connection between an inflammatory response by the body's own immune system and the buildup of fatty deposits, or plaque, within the blood vessels. These deposits can interfere with blood vessel function, as well as cause stroke or heart attack.

Mice without adiponectin had increased levels of inflammation and white blood cells sticking to the inside of blood vessel walls.

Now, new research has identified a natural substance secreted, ironically, by fat cells, that seems to counteract the dangerous effects of this inflammation.

The substance, a protein called adiponectin, stops white blood cells from the immune system from attaching to blood vessel walls. This may mean that a form of adiponectin could possibly be used one day to prevent the blood vessel damage caused by cardiovascular disease, obesity and diabetes.

Writing in the June 1, 2007 Journal of Clinical Investigation, Barry Goldstein, M.D., Ph.D., professor of medicine and director of the Division of Endocrinology, Diabetes and Metabolic Diseases and Rosario Scalia, M.D., Ph.D., associate professor of molecular physiology and biophysics, both of Jefferson Medical College of Thomas Jefferson University in Philadelphia, report that mice without adiponectin had increased levels of inflammation and white blood cells sticking to the inside of blood vessel walls. When they ran the same tests on animals who had been given adiponectin molecules for 10 days, they found far lower amounts of inflammation.

"This is translational work," says Dr. Scalia. "We've used a mouse model to prove adiponectin conceptually what we see in a test tube system in isolated cells is relevant to an intact physiological system. It's a necessary step before going to humans. These results suggest that perhaps restoring this protein could be important to preventing atherosclerosis and vascular disease."

Inflammation is a common feature of cardiovascular disease. Adiponectin has been shown in laboratory cultures to block some "adhesion molecules" and prevent white blood cells from attaching to the vessel wall, explains Dr. Scalia. "This is the first study to show in animals that this is one of the key mechanisms involved in this protein's anti-inflammatory effect on the vascular system," he notes. "That suggests thinking about either activating the receptors of the target of this protein or administering the fragment."

Adiponectin is a protein found in the bloodstream that originates from fat tissue. Low levels of adiponectin are associated with obesity, diabetes and heart disease. An adiponectin fragment can function within the body as an active, anti-inflammatory, notes Dr. Goldstein. "Since [it] is relatively easy to produce, it could eventually lead to clinical trials taking advantage of its effects in the vasculature in inflammation."